Enable read/write access to the BD9571MWV_BKUP_MODE_CNT register, which
is amongst others used to configure DDR Backup Power.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>